In one section of the cave, Indy is told "Only the penitent man will pass." Knowing this is some sort of Biblical riddle (and that apparently faith makes you better at solving riddles), Indy struggles for an answer before, at the last possible second, he realizes he must literally kneel down "before God" and ... do a kickass forward somersault? Yes, this is when our blink-and-you'll-miss-it moment occurs:
Originally, the hat was going to get buzzed and and turned into a fedora visor.
A blade whizzes past at neck height, forcing Indy to his knees. Any non-kneeling heretic would find themselves neatly decapitated. But the reason he has to then roll forward is that a second blade flies up from the floor.
That makes no sense whatsoever. Why would a penitent man also be a skilled tumbler with lightning-fast reflexes? Is the 11th Commandment that one must become an expert in P90X so you may answer the call? And how the heck did Indy even know that would happen? The answer, it appears, is that he would have been fine if he'd just knelt -- the second blade would whip in front of him, though close enough to graze his knees. So what's the point of it?